Word Origin & History

idiot c.1300, "person so mentally deficient as to be incapable of ordinary reasoning," from O.Fr. idiote "uneducated or ignorant person," from L. idiota "ordinary person, layman," in L.L. "uneducated or ignorant person," from Gk. idiotes "layman, person lacking professional skill," lit. "private person," used patronizingly for "ignorant person," from idios "one's own" (see idiom)."Reader, suppose you were an idiot. And suppose you were a member of Congress. But I repeat myself." [Mark Twain, c.1882]Idiot box "television set" is from 1959; idiot light "dashboard warning signal" is attested from ...1968. Idiocy (1487) is perhaps modeled on prophet/prophecy.